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on Microeconomics |
| By: | Eric Danan (THEMA - Théorie économique, modélisation et applications - CNRS : UMR8184 - Université de Cergy Pontoise); Thibault Gajdos (GREQAM - Groupement de Recherche en Économie Quantitative d'Aix-Marseille - Université de la Méditerranée - Aix-Marseille II - Université Paul Cézanne - Aix-Marseille III - École des Hautes Études en Sciences Sociales (EHESS) - CNRS : UMR7316); Jean-Marc Tallon (CES - Centre d'économie de la Sorbonne - CNRS : UMR8174 - Université Paris I - Panthéon-Sorbonne, EEP-PSE - Ecole d'Économie de Paris - Paris School of Economics - Ecole d'Économie de Paris) |
| Abstract: | We provide a generalization of Harsanyi (1955)'s aggregation theorem to the case of incomplete preferences at the individual and social level. Individuals and society have possibly incomplete expected utility preferences that are represented by sets of expected utility functions. Under Pareto indifference, social preferences are represented through a set of aggregation rules that are utilitarian in a generalized sense. Strengthening Pareto indifference to Pareto preference provides a refinement of the representation. |
| Keywords: | Incomplete preferences; aggregation; expected multi-utility; utilitarianism |
| Date: | 2014–01 |
| URL: | http://d.repec.org/n?u=RePEc:hal:journl:halshs-00941799&r=mic |
| By: | Ezra Einy (BGU); Ori Haimanko (BGU); Ram Orzach (Oakland University, USA); Aner Sela (BGU) |
| Abstract: | We study two-player common-value all-pay auctions (contests) with asymmetric information under the assumption that one of the players has an information advantage over his opponent and both players are budget-constrained. We generalize the results for all-pay auctions with complete information, and show that in all-pay auctions with asymmetric information, sufficiently high (but still binding) bid caps do not change the players' expected total effort compared to the benchmark auction without any bid cap. Furthermore, we show that there are bid caps that increase the players' expected total effort compared to the benchmark. Finally, we demonstrate that there are bid caps which may have an unanticipated effect on the players' expected payoffs - one player's information advantage may turn into a disadvantage as far as his equilibrium payoff is concerned. |
| Keywords: | Common-value all-pay auctions, asymmetric information, information advantage, bid caps. |
| JEL: | C72 D44 D82 |
| Date: | 2014 |
| URL: | http://d.repec.org/n?u=RePEc:bgu:wpaper:1402&r=mic |
| By: | Noé Biheng (CES - Centre d'économie de la Sorbonne - CNRS : UMR8174 - Université Paris I - Panthéon-Sorbonne, EEP-PSE - Ecole d'Économie de Paris - Paris School of Economics - Ecole d'Économie de Paris); Jean-Marc Bonnisseau (CES - Centre d'économie de la Sorbonne - CNRS : UMR8174 - Université Paris I - Panthéon-Sorbonne, EEP-PSE - Ecole d'Économie de Paris - Paris School of Economics - Ecole d'Économie de Paris) |
| Abstract: | We consider a family of exchange economies where consumers have multiprior preferences representing their ambiguity aversion. Under a linear independence assumption, we prove that regular economies are generic. Regular economies exhibit enjoyable properties: odd finite number of equilibrium prices, local constancy of this number and local differentiable selections of the equilibrium prices. Thus, even if ambiguity aversion is represented by non-differentiable multiprior preferences, economies retain generically the properties of the differentiable approach. |
| Keywords: | Demand function; general equilibrium; ambiguity aversion; multiprior preferences; regular economies; Lipschitz behavior |
| Date: | 2013–12 |
| URL: | http://d.repec.org/n?u=RePEc:hal:journl:halshs-00922782&r=mic |
| By: | Manuel Förster (CES - Centre d'économie de la Sorbonne - CNRS : UMR8174 - Université Paris I - Panthéon-Sorbonne, CORE - Center of Operation Research and Econometrics [Louvain] - Université Catholique de Louvain (UCL) - Belgique); Ana Mauleon (CORE - Center of Operation Research and Econometrics [Louvain] - Université Catholique de Louvain (UCL) - Belgique, CEREC - Université Saint-Louis - Bruxelles); Vincent Vannetelbosch (CORE - Center of Operation Research and Econometrics [Louvain] - Université Catholique de Louvain (UCL) - Belgique, CEREC - Université Saint-Louis - Bruxelles) |
| Abstract: | We investigate the role of manipulation in a model of opinion formation where agents have opinions about some common question of interest. Agents repeatedly communicate with their neighbors in the social network, can exert some effort to manipulate the trust of others, and update their opinions taking weighted averages of neighbors' opinions. The incentives to manipulate are given by the agents' preferences. We show that manipulation can modify the trust structure and lead to a connected society, and thus, make the society reaching a consensus. Manipulation fosters opinion leadership, but the manipulated agent may even gain influence on the long-run opinions. In sufficiently homophilic societies, manipulation accelerates (slows down) convergence if it decreases (increases) homophily. Finally, we investigate the tension between information aggregation and spread of misinformation. We find that if the ability of the manipulating agent is weak and the agents underselling (overselling) their information gain (lose) overall influence, then manipulation reduces misinformation and agents converge jointly to more accurate opinions about some underlying true state. |
| Keywords: | Social networks; trust; manipulation; opinion leadership; consensus; wisdom of crowds |
| Date: | 2013–09 |
| URL: | http://d.repec.org/n?u=RePEc:hal:journl:halshs-00881145&r=mic |
| By: | Pierre Chaigneau; Alex Edmans; Daniel Gottlieb |
| Abstract: | This paper shows that the informativeness principle does not automatically extend to settings with limited liability. Even if a signal is informative about effort, it may have no value for contracting. An agent with limited liability is paid zero for certain output realizations. Thus, even if these output realizations are accompanied by an unfavorable signal, the payment cannot fall further and so the principal cannot make use of the signal. Similarly, a principal with limited liability may be unable to increase payments after a favorable signal. We derive necessary and sufficient conditions for signals to have positive value. Under bilateral limited liability and a monotone likelihood ratio, the value of information is non-monotonic in output, and the principal is willing to pay more for information at intermediate output levels. |
| JEL: | D86 J33 |
| Date: | 2014–09 |
| URL: | http://d.repec.org/n?u=RePEc:nbr:nberwo:20456&r=mic |
| By: | Herve Moulin; Indrajit Ray; Sonali Sen Gupta |
| Abstract: | We consider the well-analyzed abatement game (Barrett 1994) and prove that correlation among the players (nations) can strictly improve upon the Nash equilibrium payoffs. As these games are potential games, correlated equilibrium — CE — (Aumann 1974, 1987) cannot improve upon Nash; however we prove that coarse correlated equilibria — CCE — (Moulin and Vial 1978) may do so. We compute the largest feasible total utility and hence the efficiency gain in any CCE in those games: it is achieved by a lottery over only two pure strategy profiles. |
| Keywords: | Abatement game, Coarse correlated equilibrium, Efficiency gain |
| JEL: | C72 Q52 |
| Date: | 2014 |
| URL: | http://d.repec.org/n?u=RePEc:lan:wpaper:68684722&r=mic |
| By: | Mimra, Wanda; Wambach, Achim |
| Abstract: | Riley (1979)'s reactive equilibrium concept addresses problems of equilibrium existence in competitive markets with adverse selection. The game-theoretic interpretation of the reactive equilibrium concept in Engers and Fernandez (1987) yields the Rothschild-Stiglitz (1976)/Riley (1979) allocation as an equilibrium allocation, however multiplicity of equilibrium emerges. In this note we imbed the reactive equilibrium's logic in a dynamic market context with active consumers. We show that the Riley/Rothschild-Stiglitz contracts constitute the unique equilibrium allocation in any pure strategy subgame perfect Nash equilibrium. |
| Keywords: | asymmetric information,competitive insurance market,contract addition,reactive equilibrium |
| JEL: | C72 D82 G22 L10 |
| Date: | 2014 |
| URL: | http://d.repec.org/n?u=RePEc:zbw:cfswop:483&r=mic |
| By: | Georg Nöldeke; Larry Samuelson (University of Basel) |
| Abstract: | We study markets in which agents first make investments and are then matched into potentially productive partnerships. Equilibrium investments and the equilibrium matching will be efficient if agents can simultaneously negotiate investments and matches, but we focus on markets in which agents must first sink their investments before matching. Additional equilibria may arise in this sunk-investment setting, even though our matching market is competitive. These equilibria exhibit inefficiencies that we can interpret as coordination failures. All allocations satisfying a constrained efficiency property are equilibria, and the converse holds if preferences satisfy a separability condition. We identify sufficient conditions (most notably, quasiconcave utilities) for the investments of matched agents to satisfy an exchange efficiency property as well as sufficient conditions (most notably, a single crossing property) for agents to be matched positive assortatively, with these conditions then forming the core of sufficient conditions for the efficiency of equilibrium allocations. |
| Date: | 2014 |
| URL: | http://d.repec.org/n?u=RePEc:bsl:wpaper:2014/07&r=mic |
| By: | Laurent Bouton; Aniol Llorente-Saguer; Frédéric Malherbe |
| Abstract: | A group of agents wants to reform the status quo if and only if this is Pareto improving. Agents have private information and may have common or private objectives, which creates a tension between information aggregation and minority protection. We analyze a simple voting system - majority rule with veto power (Veto) - that essentially resolves this tension, for it combines the advantageous properties of both majority and unanimity rules. We argue that our results shed new light on the evolution of voting rules in the EU institutions and could help to inform debates about policy reforms in cases such as juries in the US. |
| JEL: | D70 |
| Date: | 2014–08 |
| URL: | http://d.repec.org/n?u=RePEc:nbr:nberwo:20417&r=mic |
| By: | Colla De-Robertis, Esteban |
| Abstract: | In this paper I consider the issue of optimal information aggregation for timing decision making. In each period, a decision maker may choose an action which delivers an uncertain payoff, or wait until the next period, in when new information will arrive. The information is provided by a committee of experts. Each member in each period receives a signal correlated to the state. I obtain an optimal rule for aggregating information for each period. |
| Keywords: | Information aggregation. Timing decision making. Experts. |
| JEL: | D7 D81 |
| Date: | 2014–11–09 |
| URL: | http://d.repec.org/n?u=RePEc:pra:mprapa:59836&r=mic |
| By: | Ahmet Ozkardas (CES - Centre d'économie de la Sorbonne - CNRS : UMR8174 - Université Paris I - Panthéon-Sorbonne); Agnieszka Rusinowska (CES - Centre d'économie de la Sorbonne - CNRS : UMR8174 - Université Paris I - Panthéon-Sorbonne) |
| Abstract: | We provide an equilibrium analysis of a wage bargaining model between a union and a firm in which the union must choose between strike and holdout in case of a disagreement. While in the literature it is assumed that the parties of wage bargaining have constant discount factors, in our model preferences of the union and the firm are expressed by sequences of discount rates varying in time. First, we describe necessary conditions under arbitrary sequences of discount rates for the supremum of the union's payoffs and the infimum of the firm's payoffs under subgame perfect equilibrium in all periods when the given party makes an offer. Then, we determine the equilibrium payoffs for particular cases of sequences of discount rates varying in time. Besides deriving the exact bounds of equilibrium payoffs, we also characterize the equilibrium strategy profiles that support these extreme payoffs. |
| Keywords: | Union; firm bargaining; varying discount rates; subgame perfect equilibrium; equilibrium payoffs |
| Date: | 2014–02 |
| URL: | http://d.repec.org/n?u=RePEc:hal:journl:halshs-00971403&r=mic |
| By: | Kodritsch, Sebastian |
| Abstract: | This paper analyzes dynamically inconsistent time preferences in Rubinstein's (1982) seminal model of bargaining. When sophisticated bargainers have time preferences that exhibit a form of present bias - satisfied by the hyperbolic and quasi-hyperbolic time preferences increasingly common in the economics literature - equilibrium is unique and lacks delay. However, when one bargainer is more patient about a single period's delay from the present than one that occurs in the near future, the game permits a novel form of equilibrium multiplicity and delay. Time preferences with this property have most recently been empirically documented; they can also arise when parties who weight probabilities non-linearly bargain under the shadow of exogenous breakdown risk, as well as in settings of intergenerational bargaining with imperfect altruism. The paper's main contributions are (i) a complete characterization of the set of equilibrium outcomes and payoffs for separable time preferences, and (ii) present bias as a readily interpretable sufficient condition for uniqueness at the level of individual preferences. |
| Keywords: | bargaining,time preference,dynamic inconsistency,delay |
| JEL: | C78 D03 D74 |
| Date: | 2014 |
| URL: | http://d.repec.org/n?u=RePEc:zbw:wzbmbh:spii2014205&r=mic |
| By: | Antoine Billot (EEP-PSE - Ecole d'Économie de Paris - Paris School of Economics - Ecole d'Économie de Paris, PSE - Paris-Jourdan Sciences Economiques - CNRS : UMR8545 - École des Hautes Études en Sciences Sociales (EHESS) - École des Ponts ParisTech (ENPC) - École normale supérieure [ENS] - Paris - Institut national de la recherche agronomique (INRA), LEMMA - Laboratoire d'économie mathématique et de microéconomie appliquée - Université Paris II - Panthéon-Assas : EA4442 - Sorbonne Universités); Vassili Vergopoulos (EEP-PSE - Ecole d'Économie de Paris - Paris School of Economics - Ecole d'Économie de Paris, CES - Centre d'économie de la Sorbonne - CNRS : UMR8174 - Université Paris I - Panthéon-Sorbonne) |
| Abstract: | This paper seeks to interpret observable behavior and departures from Savage's model of Subjective Expected Utility (SEU) in terms of knowledge and belief. It is shown that observable behavior displays sensitivity to ambiguity if and only if knowledge and belief disagree. In addition, such an epistemic interpretation of ambiguity leads to dynamically consistent extensions of non-SEU preferences. |
| Keywords: | Ambiguity; state of world; knowledge; dynamic consistency |
| Date: | 2014–03 |
| URL: | http://d.repec.org/n?u=RePEc:hal:journl:halshs-01021392&r=mic |
| By: | Martin Gregor (Institute of Economic Studies, Faculty of Social Sciences, Charles University in Prague, Smetanovo nábreží 6, 111 01 Prague 1, Czech Republic) |
| Abstract: | We study a game in which a sender with verifiable private information has to pay an access fee that is announced by a receiver to be able to convey her message to the receiver. The setting is motivated by the literature of pay-and-lobby politics, which finds that politicians decide to schedule informative meetings with lobbyists on the basis of their campaign contributions. We solve the game for all timings, prior beliefs, and noise and valuation parameters. We identify the receiver's tradeoff between the amount of information and the amount of revenue. At the tradeoff, the receiver decides to not receive an informative signal from the sender. Whether `burying one's head in the sand' increases or decreases welfare depends on the degree of the receiver's benevolence. |
| Keywords: | disclosure, persuasion, hard evidence, access fee, lobbying |
| JEL: | C72 C78 D72 D83 |
| Date: | 2014–05 |
| URL: | http://d.repec.org/n?u=RePEc:fau:wpaper:wp2014_17&r=mic |
| By: | Felipe Balmaceda (Facultad de Economía y Empresa, Universidad Diego Portales); Santiago Balseiro (The Fuqua School of Business, Duke University); Jose Correa (Departamento de Ingenieria Industrial, Universidad de Chile); Nicolas Stier-Moses (Columbia School of Business, Columbia University) |
| Abstract: | This article studies a principal-agent problem with discrete outcome and effort level spaces. The principal and the agent are risk neutral and the latter is subject to limited liability. We consider the ratio between the first-best social welfare to the social welfare arising from the principal’s optimal pay-for-performance contract, i.e., the welfare loss. In the presence of moral hazard, we provide simple parametric bounds on the welfare loss of a given instance, and then study the worst-case welfare loss among all instances with a fixed number of effort and outcome levels. Key parameters to these bounds are the number of possible effort levels, the likelihood ratio evaluated at the highest outcome, and the ratio between costs of the highest and the lowest effort levels. As extensions, we also look at linear contracts and at cases with multiple identical tasks. Our work constitutes an initial effort to analyze losses arising from moral hazard problems when the agent is subject to limited liability, and shows that these losses can be costly in the worst case. |
| Date: | 2014–09 |
| URL: | http://d.repec.org/n?u=RePEc:ptl:wpaper:55&r=mic |
| By: | Athanasopoulos, Thanos (Department of Economics, University of Warwick) |
| Abstract: | This paper investigates the relation between firms’R&D incentives and their compatibility decisions regarding durable, imperfectly substitutable network goods in the presence of forward looking consumers. Non drastic product innovation is sequential and both an initially dominant firm and a smaller rival are potential inventors. For sufficiently innovative future products, our first key result is that the dominant firm invests more when there is compatibility and voluntarily decides to supply interoperability information. This happens as the probability that he is the only inventor increases, allowing him to enjoy a higher expected future profit that outweighs the current lost revenue. For economies whose initial market size is considerably large, the rival also demands compatibility but this is no longer true in industries with a relatively smaller number of existing consumers. For less innovative new versions, the dominant firm rejects compatibility and there is a cutoff in network externalities below which he invests more when there is incompatibility. Regarding welfare, we find that a laissez faire Competition Law with respect to the IPR holders is socially preferable. |
| Date: | 2014 |
| URL: | http://d.repec.org/n?u=RePEc:wrk:warwec:1054&r=mic |
| By: | Nizar Allouch (Queen Mary University of London); Myrna Wooders (Vanderbilt University) |
| Abstract: | We provide a new proof of the non-emptiness of approximate cores of games with many players of a finite number of types. Earlier papers in the literature proceed by showing that, for games with many players, equal-treatment cores of their "balanced cover games", which are non-empty, can be approximated by equal-treatment ε-cores of the games themselves. Our proof is novel in that we rely on a fixed point theorem. |
| Keywords: | NTU games, Core, Approximate cores, Small group effectiveness, Coalition formation, Payoff dependent balancedness |
| JEL: | C71 C78 D71 |
| Date: | 2014–09 |
| URL: | http://d.repec.org/n?u=RePEc:qmw:qmwecw:wp726&r=mic |
| By: | Bannier, Christina E.; Feess, Eberhard; Packham, Natalie |
| Abstract: | This paper examines the effect of imperfect labor market competition on the efficiency of compensation schemes in a setting with moral hazard, private information and risk-averse agents. Two vertically differentiated firms compete for agents by offering contracts with fixed and variable payments. Vertical differentiation between firms leads to endogenous, type-dependent exit options for agents. In contrast to screening models with perfect competition, we find that existence of equilibria does not depend on whether the least-cost separating allocation is interim efficient. Rather, vertical differentiation allows the inferior firm to offer (cross-)subsidizing fixed payments even above the interim efficient level. We further show that the efficiency of variable pay depends on the degree of competition for agents: For small degrees of competition, low-ability agents are under-incentivized and exert too little effort. For large degrees of competition, high-ability agents are over-incentivized and bear too much risk. For intermediate degrees of competition, however, contracts are second-best despite private information. |
| Keywords: | Incentive compensation,screening,imperfect labor market competition,vertical differentiation,cross-subsidy |
| JEL: | D82 D86 J31 J33 |
| Date: | 2014 |
| URL: | http://d.repec.org/n?u=RePEc:zbw:cfswop:475&r=mic |
| By: | Alex Barrachina (University Carlos III, Madrid, Spain); Yair Tauman (IDC Herzliya, Israel, and Stony Brook University, USA); Amparo Urbano Salvador (ERI-CES, University of Valencia) |
| Abstract: | We analyze the effect of industrial espionage on limit-pricing models. We consider an incumbent monopolist engaged in R&D trying to reduce his cost of production and deter a potential entrant from entering the market. The R&D project may be successful or not and its outcome is a private information of the incumbent. The entrant has an access to an Intelligence System (IS hereafter) of a certain precision that generates a noisy signal on the outcome of the R&D project, and she decides whether to enter the market based on two signals: the price charged by the incumbent and the signal sent by the IS. It is assumed that the precision of the IS is exogenous and common knowledge. Our fundamental result is that for intermediate values of the IS precision, the set of pooling equilibria is non-empty even with profitable entry and the entrant enters if the IS tells her the R&D project was not successful. Since in the classical limit-pricing models the entrant never enters in a pooling equilibrium, the use of the IS by the entrant increases competition in pooling equilibrium with high probability. Moreover, the incumbent can deter profitable entry with positive probability. |
| Keywords: | Espionage, Entry deterrence, Asymmetric information, Pooling equilibria. |
| JEL: | C72 D82 L10 L12 |
| Date: | 2014–11 |
| URL: | http://d.repec.org/n?u=RePEc:dbe:wpaper:0714&r=mic |
| By: | Mark Dean; Ozgur Kibris; Yusufcan Masatlioglu |
| Abstract: | We introduce and axiomatically characterize a model of status quo bias in which the status quo affects choices by both changing preferences and focusing attention. The resulting Limited Attention Status Quo Bias model can explain both the finding that status quo bias is more prevalent in larger choice sets and that the introduction of a status quo can change choices between non-status quo alternatives. Existing models of status quo bias are inconsistent with the former finding while models of decision avoidance are inconsistent with the latter. We report the results of laboratory experiments which show that both attention and preference channels are necessary to explain the impact of status quo on choice. |
| Keywords: | Status Quo Bias, Reference Dependence, Attention, Revealed Preference |
| Date: | 2014 |
| URL: | http://d.repec.org/n?u=RePEc:bro:econwp:2014-11&r=mic |
| By: | Benjamin Hébert |
| Abstract: | Abstract. Why are debt securities so common? I show that debt securities minimize the welfare losses from the moral hazards of excessive risk-taking and lax effort. For any security design, the variance of the security payoff is a statistic that summarizes these welfare losses. Debt securities have the least variance, among all limited liability securities with the same expected value. The optimality of debt is exact in my benchmark model, and holds approximately in a wide range of models. I study both static and dynamic security design problems, and show that these two types of problems are equivalent. The models I develop are motivated by moral hazard in mortgage lending, where securitization may have induced lax screening of potential borrowers and lending to excessively risky borrowers. My results also apply to corporate finance and other principal-agent problems. |
| Date: | 2014–02 |
| URL: | http://d.repec.org/n?u=RePEc:qsh:wpaper:145746&r=mic |
| By: | Joshua Gans; Fiona Murray |
| Abstract: | Formal attribution provides a means of recognizing scientific contributions as well as allocating scientific credit. This paper examines the processes by which attribution arises and its interaction with market assessments of the relative contributions of members of scientific teams and communities – a topic of interest organizational economics of science and in understanding scientific labor markets. We demonstrate that a pioneer or senior scientist’s decision to co-author with a follower or junior scientist depends critically on market attributions as well as the timing of the co-authoring decision. This results in multiple equilibrium outcomes each with different implications for expected quality of research projects. However, we demonstrate that the Pareto efficient organisational regime is for the follower researcher to be granted co-authorship contingent on their own performance without any earlier pre-commitment to formal attribution. We then compare this with the alternative for the pioneer of publishing their contribution and being rewarded through citations to back to it. While in some equilibria (especially where co-authoring commitments are possible) there is no advantage to interim publication, in others this can increase expected research quality. |
| JEL: | O31 O34 |
| Date: | 2014–11 |
| URL: | http://d.repec.org/n?u=RePEc:nbr:nberwo:20677&r=mic |
| By: | Demuynck T.; Seel C. (GSBE) |
| Abstract: | We derive revealed preference tests for models where individuals use consideration sets to simplify their consumption problem. Our basic test provides necessary and sufficient conditions for consistency of observed choices with the existence of consideration set restrictions. The same conditions can also be derived from a model in which the consideration set formation is endogenous and based on subjective, unconstrained beliefs about the prices. By imposing restrictions on these subjective beliefs, we obtain additional refined revealed preference tests. We illustrate and compare the performance of our tests by means of a dataset on household consumption choices. |
| Keywords: | Consumer Economics: Theory; Consumer Economics: Empirical Analysis; Criteria for Decision-Making under Risk and Uncertainty; |
| JEL: | D11 D12 D81 |
| Date: | 2014 |
| URL: | http://d.repec.org/n?u=RePEc:unm:umagsb:2014036&r=mic |
| By: | Joshua S. Gans |
| Abstract: | In a dynamic environment where underlying competition is "for the market," this paper examines what happens when entrants and incumbents can instead negotiate for the market. For instance, this might arise when an entrant innovator can choose to license to or be acquired by an incumbent firm; i.e., engage in cooperative commercialization. It is demonstrated that, depending upon the level of firms' potential dynamic capabilities, there may or may not be gains to trade between incumbents and entrants in a cumulative innovation environment; that is, entrants may not be adequately compensated for losses in future innovative potential. This stands in contrast to static analyses that overwhelmingly identify positive gains to trade from such cooperation. |
| JEL: | O31 O32 O34 |
| Date: | 2014–10 |
| URL: | http://d.repec.org/n?u=RePEc:nbr:nberwo:20559&r=mic |